1. Field of the Invention
The present invention relates to a barrel-type coating apparatus suitable for the bulk treatment of small parts such as sliders and end stops of slide fasteners, buttons, hook-and-eye fasteners, ornaments or the like.
2. Prior Art
A typical example of known coating apparatus of the type described is shown in FIG. 12 of the accompanying drawings. The apparatus includes a cup-like drum 13 pivotably supported on a frame 14 and normally held in an upwardly tilted position, a barrel 15 rotatably mounted in a drum 13, an exhaust duct 16 disposed above the drum 13, and a paint-spraying nozzle 17 and a hot-air blowing nozzle 18 which are disposed adjacent to an open end 19 of the drum 13. In operation, a batch of parts is put into the barrel 15 while being rotated, and paint is sprayed from the nozzle 17 onto the parts in the rotating barrel 15. The coated paint on the parts is set and baked by hot air blown from the nozzle 18 into the barrel 15. Then the hot air in the barrel 15 is expelled through the exhaust duct 16 to cool the baked paint on the parts. The barrel 15 is continuously rotated during the baking and cooling steps. Finally, the drum 13 is tilted downwardly to discharge the parts from the barrel 15.
With the apparatus thus constructed, all the paint-spraying, setting, baking and cooling steps are carried out in the drum 13, with the result that the barrel atmosphere must be expelled from the barrel 15 before the baking and cooling steps are started. Such construction causes a great loss of heat energy and requires a relatively long processing time, resulting in reduction of productivity.